The invention is particularly useful for dispensing single units of conical paper articles such as filter papers shaped for use in funnels. Common filter paper is typically a cellulose product which is permeable to water and gases, to enable separation of solids from a fluid stream. For low volume intermittent liquid-solid separations, a typical filtering method involves inserting a cone of filter paper into a funnel and pouring the liquid through the funnel.
Conical filters are widely used in industrial laboratories, and so forth to effect or maintain separations. They are also used widely domestically to make coffee drink, and the present invention is particularly suited to the needs attending such use. Such filters come in different configurations, but most popularly they are provided in the form of pleated, truncated circular cones of about 5 inch diameter by 2-3 inch depth. The filter paper thickness is in the range of 0.004 inch. The conical filters are typically sold in quantities of 50-100, nested together, in a loose plastic bag or simple hinged cover box with base or open end upward.
For many people, especially the elderly, it is difficult to readily separate only one of the thin filters from the nested bulk; often several filters will be inadvertantly picked off. If several are used in the coffee-making funnel, there is both more waste and a lower flow rate--and possible liquid overflow, than there ought to be.
Suppliers of filters have recognized the separation problem. Some have provided low cost plastic tweezers, with and without rubber tips, in the filter package. The intent appears that the tweezers be used to grasp the innermost of the nested filters at the truncated end, or closed end, of the cone. Nonetheless, a certain dexterity and skill is still required to obtain just one filter.
U.S. Pat. No. 4,214,673 to Heath et al. shows a filter dispenser having a lid with a slidable arm extending into the concavity of nested filters contained therein. When actuated against a spring, the adhesive tipped arm engages the interior of a filter. Lifting the hinged lid causes a filter to be dragged upward. U.S. Pat. No. 4,629,029 to English shows a like construction where the tip is surfaced with abrasive. U.S. Pat. No. 4,121,726 to Pemberton shows a device that is somewhat similar, having a mechanically pivoted lever with a sharp pointed tip to engage the filters; stops around the side walls retain the filter nest in the container. The foregoing devices are comparatively costly to make, in the context of the low cost of filters, and are not suitably made of low cost materials such as cardboard.
U.S. Pat No. 4,739,902 of Joslyn et al. shows a coffee filter dispenser with several features in common with the present invention; it is made of cardboard and has a hinged lid which is die cut from the top cover. A tab, diecut into the hinged lid, hinges from the outer portion of the lid. The tab is surfaced with adhesive and adheres to a filter, as in the other patented devices, when the tab is pushed into the interior of the filter nest contained in the dispenser. When the lid is raised, a filter is pulled out; remainder portions of the top cover act as stops, to retain the filter nest as the topmost filter is drawn out.
However, all the filter dispensers which use adhesive suffer the disadvantage that there is an accumulation of filter debris over time, lessening their effectiveness. Further, unlike the slidable lever devices, the container of Joslyn tends to not automatically provide a closed container which protects the contents from debris, since after several times of use, the tab tends to sag and remain depressed within the box.
Thus, there is a need for a better system by which a user can separate a filter from a bulk mass of filters. The dispenser will have a low cost, consistent with the price of the filter papers. Ideally, the device will also be amenable to being either the container in which the filter papers are sold, or to being collapsible and economically shipped for separate mail order sale.